package org.ops.ui.editor.swing.ash;

/*
 * TokenMarker.java - Generic token marker
 * Copyright (C) 1998, 1999 Slava Pestov
 *
 * You may use and modify this package for any purpose. Redistribution is
 * permitted, in both source and binary form, provided that this notice
 * remains intact in all source distributions of this package.
 */

import javax.swing.text.Segment;
import java.util.*;

/**
 * A token marker that splits lines of text into tokens. Each token carries
 * a length field and an indentification tag that can be mapped to a color
 * for painting that token.<p>
 *
 * For performance reasons, the linked list of tokens is reused after each
 * line is tokenized. Therefore, the return value of <code>markTokens</code>
 * should only be used for immediate painting. Notably, it cannot be
 * cached.
 *
 * @author Slava Pestov
 * @version $Id: TokenMarker.java,v 1.1 2007-02-26 20:29:00 meboyce Exp $
 *
 * @see org.gjt.sp.jedit.syntax.Token
 */
public abstract class TokenMarker {
  /**
   * A wrapper for the lower-level <code>markTokensImpl</code> method
   * that is called to split a line up into tokens.
   * @param line The line
   * @param lineIndex The line number
   */
  public Token markTokens(Segment line, int lineIndex) {
    if(lineIndex >= length) {
      throw new IllegalArgumentException("Tokenizing invalid line: "
          + lineIndex);
    }

    lastToken = null;

    LineInfo info = lineInfo[lineIndex];
    LineInfo prev;
    if(lineIndex == 0)
      prev = null;
    else
      prev = lineInfo[lineIndex - 1];

    byte oldToken = info.token;
    byte token = markTokensImpl(prev == null ?
        Token.NULL : prev.token,line,lineIndex);

    info.token = token;

    /*
     * This is a foul hack. It stops nextLineRequested
     * from being cleared if the same line is marked twice.
     *
     * Why is this necessary? It's all AshConsole's fault.
     * When something is inserted into the text, firing a
     * document event, the insertUpdate() method shifts the
     * caret (if necessary) by the amount inserted.
     *
     * All caret movement is handled by the select() method,
     * which eventually pipes the new position to scrollTo()
     * and calls repaint().
     *
     * Note that at this point in time, the new line hasn't
     * yet been painted; the caret is moved first.
     *
     * scrollTo() calls offsetToX(), which tokenizes the line
     * unless it is being called on the last line painted
     * (in which case it uses the text area's painter cached
     * token list). What scrollTo() does next is irrelevant.
     *
     * After scrollTo() has done it's job, repaint() is
     * called, and eventually we end up in paintLine(), whose
     * job is to paint the changed line. It, too, calls
     * markTokens().
     *
     * The problem was that if the line started a multiline
     * token, the first markTokens() (done in offsetToX())
     * would set nextLineRequested (because the line end
     * token had changed) but the second would clear it
     * (because the line was the same that time) and therefore
     * paintLine() would never know that it needed to repaint
     * subsequent lines.
     *
     * This bug took me ages to track down, that's why I wrote
     * all the relevant info down so that others wouldn't
     * duplicate it.
     */
    if(!(lastLine == lineIndex && nextLineRequested))
      nextLineRequested = (oldToken != token);

    lastLine = lineIndex;

    addToken(0,Token.END);

    return firstToken;
  }

  /**
   * An abstract method that splits a line up into tokens. It
   * should parse the line, and call <code>addToken()</code> to
   * add syntax tokens to the token list. Then, it should return
   * the initial token type for the next line.<p>
   *
   * For example if the current line contains the start of a
   * multiline comment that doesn't end on that line, this method
   * should return the comment token type so that it continues on
   * the next line.
   *
   * @param token The initial token type for this line
   * @param line The line to be tokenized
   * @param lineIndex The index of the line in the document,
   * starting at 0
   * @return The initial token type for the next line
   */
  protected abstract byte markTokensImpl(byte token, Segment line,
      int lineIndex);

  /**
   * Returns if the token marker supports tokens that span multiple
   * lines. If this is true, the object using this token marker is
   * required to pass all lines in the document to the
   * <code>markTokens()</code> method (in turn).<p>
   *
   * The default implementation returns true; it should be overridden
   * to return false on simpler token markers for increased speed.
   */
  public boolean supportsMultilineTokens() {
    return true;
  }

  /**
   * Informs the token marker that lines have been inserted into
   * the document. This inserts a gap in the <code>lineInfo</code>
   * array.
   * @param index The first line number
   * @param lines The number of lines
   */
  public void insertLines(int index, int lines) {
    if(lines <= 0)
      return;
    length += lines;
    ensureCapacity(length);
    int len = index + lines;
    System.arraycopy(lineInfo,index,lineInfo,len,
        lineInfo.length - len);

    for(int i = index + lines - 1; i >= index; i--) {
      lineInfo[i] = new LineInfo();
    }
  }

  /**
   * Informs the token marker that line have been deleted from
   * the document. This removes the lines in question from the
   * <code>lineInfo</code> array.
   * @param index The first line number
   * @param lines The number of lines
   */
  public void deleteLines(int index, int lines) {
    if (lines <= 0)
      return;
    int len = index + lines;
    length -= lines;
    System.arraycopy(lineInfo,len,lineInfo,
        index,lineInfo.length - len);
  }

  /**
   * Returns the number of lines in this token marker.
   */
  public int getLineCount() {
    return length;
  }

  /**
   * Returns true if the next line should be repainted. This
   * will return true after a line has been tokenized that starts
   * a multiline token that continues onto the next line.
   */
  public boolean isNextLineRequested() {
    return nextLineRequested;
  }

  // protected members

  /**
   * The first token in the list. This should be used as the return
   * value from <code>markTokens()</code>.
   */
  protected Token firstToken;

  /**
   * The last token in the list. New tokens are added here.
   * This should be set to null before a new line is to be tokenized.
   */
  protected Token lastToken;

  /**
   * An array for storing information about lines. It is enlarged and
   * shrunk automatically by the <code>insertLines()</code> and
   * <code>deleteLines()</code> methods.
   */
  protected LineInfo[] lineInfo;

  /**
   * The number of lines in the model being tokenized. This can be
   * less than the length of the <code>lineInfo</code> array.
   */
  protected int length;

  /**
   * The last tokenized line.
   */
  protected int lastLine;

  /**
   * True if the next line should be painted.
   */
  protected boolean nextLineRequested;

  /**
   * Creates a new <code>TokenMarker</code>. This DOES NOT create
   * a lineInfo array; an initial call to <code>insertLines()</code>
   * does that.
   */
  protected TokenMarker() {
    lastLine = -1;
  }

  /**
   * Ensures that the <code>lineInfo</code> array can contain the
   * specified index. This enlarges it if necessary. No action is
   * taken if the array is large enough already.<p>
   *
   * It should be unnecessary to call this under normal
   * circumstances; <code>insertLine()</code> should take care of
   * enlarging the line info array automatically.
   *
   * @param index The array index
   */
  protected void ensureCapacity(int index) {
    if(lineInfo == null)
      lineInfo = new LineInfo[index + 1];
    else if(lineInfo.length <= index) {
      LineInfo[] lineInfoN = new LineInfo[(index + 1) * 2];
      System.arraycopy(lineInfo,0,lineInfoN,0,
          lineInfo.length);
      lineInfo = lineInfoN;
    }
  }

  /**
   * Adds a token to the token list.
   * @param length The length of the token
   * @param id The id of the token
   */
  protected void addToken(int length, byte id) {
    if(id >= Token.INTERNAL_FIRST && id <= Token.INTERNAL_LAST)
      throw new InternalError("Invalid id: " + id);

    if(length == 0 && id != Token.END)
      return;

    if(firstToken == null) {
      firstToken = new Token(length,id);
      lastToken = firstToken;
    }
    else if(lastToken == null) {
      lastToken = firstToken;
      firstToken.length = length;
      firstToken.id = id;
    }
    else if(lastToken.next == null) {
      lastToken.next = new Token(length,id);
      lastToken = lastToken.next;
    }
    else {
      lastToken = lastToken.next;
      lastToken.length = length;
      lastToken.id = id;
    }
  }

  /**
   * Inner class for storing information about tokenized lines.
   */
  public class LineInfo {
    /**
     * The id of the last token of the line.
     */
    public byte token;

    /**
     * This is for use by the token marker implementations
     * themselves. It can be used to store anything that
     * is an object and that needs to exist on a per-line
     * basis.
     */
    public Object obj;

    /**
     * Creates a new LineInfo object with token = Token.NULL
     * and obj = null.
     */
    public LineInfo() {
    }

    /**
     * Creates a new LineInfo object with the specified
     * parameters.
     */
    public LineInfo(byte token, Object obj) {
      this.token = token;
      this.obj = obj;
    }
  }
}
